Gas-turbine unit



Filed Dec. 2, 1924 2 Sheets-Sheet l June 24, 1930. J. w. A. ELLING GASTURBINE UNIT Filed Dec. 2, 1924 2 Sheets-Sheet 2 Patented June. 24, 1930arms WILLIAM Anexmus ELLING, or c'nms'rmnra, NORWAY GAS-TURBIN E UNITApplication filed December 2, 1924, Serial No.

The gasturbines of the impulse type hitherto known are based upon thesame idea as 7 gas motors with pistons, viz. compression,

combustion and then an extensive expansion. This principle which is verywell suitable in piston motors is, however, connected with greatdifliculties in turbines. If, namely, the efiiciency shall be maintainedat a reasonable value the great kinetic energy contained in the gases ofcombustion before their passing into the turbine wheel must be transformed into a velocity so high that only with difliculty can it beutllized within the wheel,

because the. latter should not be given a higher velocity than what thematerials actually used can safely stand, and the outlet velocity willbe very high. In, addition thereto, there are inconveniences inconnection with the high temperatures andthe ex;

tra increase in temperature, to which the bl'ades'ar'e subjected.vMoreover, the high velocity of the runner requires gearing in order toenablethe utilization of. the useful work.

The starting will be difficult, and areversal will be practicallyimpossible.

The present invention has {for its object to avoid completely thedrawbacks which in the said respects have been'connected with thesystems hitherto known and this is obtained'by adivisionof the processinto two or more stages and by such an arrangement that .the work-ofcompression for the last stage independent of the preceedingstages.

or stages is effected substantially by the preceding stage or stages.pendent of one another in mechanical respect,

particularly the last stage, wherein the useful work is taken out, ismechanically quite In orderto enable the invention to beunderstood,.thesame will be described with reference to the accompanyingdrawings showing in Figures 1 to 4 diagrammatically a multi-stage systemconstructed in accord- 1 ance with the invention. Figure 5 shows amodification and Fig. 6 is a 'Rankine-dlagram 'for the, system shown.

In the drawing, Figures 1, 2, 3, 4 represent the different stages, whichhereinafter for sake of convenience will be termed shortly I,

II, III, IV. 1, 1, 1 designate gas turbines All stages are inde 753,580,and in mm December 1s, 192a.

and 2 2, 2, respectively, compressors con nppted therewith, and 1 is aturbine of stage I v The air enters the compressor 2 III (Figure 3) andis compressed therein.

Having passed out from 2 the air is cooled at 9 and passes througha couit 4 to a second compressor 2 forming e element of stage II (Figure 2).'In the second compressor the air'is further compressed and isthencooled again at -9 and passed through "conduit 4 to a thirdcompressor2 of stage 1 I Figure 1) in order to be finally compressed ofstage t 'erein. In this highly compressed stagethe I gas passes into acombustion chamber 3 into which a suitable combustible is sprayed at 10.The products of combustion are now passed through the conduit 5 to thedriving turbine 1 of stage I and from there through the conduit 5 into acombustion chamber 3?, into which a combustible is sprayed at 10*, andtheythen pass through the turbine 1 of stage II. From the latter thegases are passing further through the conduit 5 to the turbine 1 ofstage III preferably without pass-' 'ing through'any further combustioncham- -'ber. The gas expanded in the turbine of stage III may thenbeassed through conduits 5 to a driving tur ine 1, for instance for adynamo 6, or. to piston motors 7, 7 (Figure 5),

Thecompressors of each stage are coupled directly to turbines and thevelocity is control y a separate governor at each stageas indicated at8, 8

a -Thus the compressor 2 is coupled mechan- .ically to turbine 1 ofstage'L-compressor 2 of stage II,yand compressor 2" to turbine 1toturbine 1 of stageIII, and all these three stages are independentof'each other'in mechanical respect.

By means of the diagram of Figured the operation will be clearlyunderstood; In this rag-ram the abscissas representvolumeof air sure inthe ordinary manner. The horizontal .bottom 'llnerepresents theabsolutezero-pressure and the next horizontal line above same representsthe atmosphericpressure, wherefor the res ective stages Ital,

I and gases, and the ordinates'represent pres- Thus the curve 11-12represents the usefulwork of compression. The gross work of compressionis represented by the curve 11-12', it being assumed that the work 11-12be 75% of thework 11'-12' corresponding to an efliciency of 75% in thecompressor. The air from 2 has a temperature of 104 C. and is cooled at.9 to a temperature of say 17 C. (12-13, Figure 6). Then it passes intocompressor 2 and isfurt-her compressed corresponding to a rise intemperature from 17 to 104 C. The curves 13-14 I and 13'-14 representthe corresponding as compared with the initial pressure (1 at to thetemperature (310 'C.)

the outlet from turbine 1".

useful and ross work of com ression respectively. ooling is again eected at 9' down to 17 (14-15, Figure 6) and then a final compression iseffected in compressor 2 from 17 to 104. Thecurves 15-16 and 15'16'represent the corresponding useful and gross work of compressionrespectively.

'At 10 the compressed air receives heat, whereby its temperature israised to 490 (16-47, Fi ure 6) and is then'expandedin turbine 1. Ihecurve 17-18 represent-s the gross and curve 17 -18' useful or net workof expansion, it being assumed that the work 17 '-18' is 85% of the work17-18. At 10" the partly expanded gases receive heat energy and areraised from 400 to 490. A further expansion (from 490 to 400) takesplace in turbine 1, the gross and net works of expansion, beingrepresented by curves 19-20 and 19'-20' respectively. From turbine 1*the gases pass directl to turbine 1 in order to be furtherv expan ed(from 400 310 0.), the gross and net work of expan'sion beingrepresented by the curves 20-21 and 20-21' respectively. The gases arenow prepared for exerting useful work in the engine 1, having anincreased pressure mosphere) before the compression and having also anincreased volume corresponding revailing at T is prepared aseous drivingfluid can therefore be utilized n any suitable engine, either a fourthturbine 1 for driving the dynamo 6 (Figure 4) or a plurality of pistonmotors 7, 7 (Figure 5).

As will be seen from the drawing the engine 1 or 7, is not mechanicallycoupled to the aggregates of the stages I, II, III, but is mechanicallyquite independent thereof.

Consequently the transferring engine thus ing,

can be retarded, accelerated, stopped and I even reversed independentlyof the rotating masses of the first three. stages and independently ofthe working conditions thereof. The manipulation of the engine thereforecan be effected very easily and with a reasonable mass, because therotating masses of the said three stages will in no way take part ofsuch manipulation but can run with unaltered speed and in a constantdirection of rotation. Obviously this result is of great practicalimportance. Moreover, as the driving fluid entering the engine throughconduit 5 has a comparatively low pressure but a large volume, it can beutilized in the turbine 1 with a reasonable peripheric velocity'and sizeof this turbine, consequently at a moderate number of revolutions,

whereby in many cases gearing between the engine, such as 1 or 7, andthe driven machine such as 6, can be avoided.

I have pointed out above that engine 1 or 7 is mechanically independentof stages I,

II and III, but it is also very well ossible to make the several stagesI, II, II indendent of one another mutually. .In fact, ust thisconstruction is shown. in the drawwherein the shaft of machines 1, 2 ofstage I, shaft of 1",, 2 of stage II and shaft of 1 2 of stage III arewithout any mechanical connection with one another. Each shaft thereforecan be run with the most suitable number of revolutions.

From the diagram, Figure 6, will be seen thatv the net work of expansionof turbine 1 (curve 17 18) is equal to the gross work of compression ofcompressor 2 (curve 15'-16' it being-easy to arrange the conditions inthis manner, wherebythe energy taken by turbine 1 is just consumed bythe compression energy absorbed in compressor 2 and by frictionresistances, losses of heat, etc. 7 Consequently no work will bedelivered out from stage I, and only the energy contained in the outletgases from turbine 1 will be transported on to the next stage II.

In this stage the conditions are just similar.

to those of stage I, because the net work of expansion of turbine 1(curve 19'-20') is equal to the gross work of compression of compressor2 (curve 13'-14'). Finally, in stage III the network of expansion ofturbine 1" (curve 20'--21') is equal to the gross work of compression ofcompressor 2" (curve 11-124 After having left turbine 1 the gases areexerting their useful work (curve 21-22) in the engine 1, 7 etc.,' whichconsequently is not hitherto loaded with any work of compression.

When all four stages I, II, III, IV are considered as a complete-unit,it will thus be seenthat the output of the different stages before thelast one may be so selected that stage in question From the differentstages I before the last one no mechanical work is taken out, and theturbines operating in each .of these stages may therefore run with justthe number ofrevolutions most convenient to the stage in question.Urfder these circumstances it is preferred: to increase the wheeldiameterthrough the stages according as" the gas volumeis increased andto reduce correspondingly the number of revolutions of the turbines ofthe successive stages. The difierent stages therefore should be providedwith separate governors indenendently of each other.

The different stage sections need not be connected to one another in anyother manner than through air pipes which connect the compressors insucceeding stages together and through gas pipes which connect theoutlet from the turbine of one Stage with the combustion chamber for theturbine of the next stage.

If the useful work ofthe gas turbine aggregate is tobe transmittedthrough a turbine which may for instance be coupled directly to thedriven machine element, this turbine erto ordinary,

proper may possess one or more stages like ordinary steam'turbines. Thetotal fall in pressure between inlet and outlet, however,

will be comparatively small and the theoretical efiiciency consequentlycorrespondingly higher.

As will be understood, it is possible in this manner to obtain a gasturbine unit of a very practical construction without using, as hithhighratios of gearing, because the' several stages I, II, III, IV aremechanically independent of each other, and consequently the number ofrevolutions in any of these stages may be chosen independently of thatof the other stages.

The starting of the diiferent stages takes place easily one after theother.

Obviously, the invention is not limited to any specific number ofstages. n c

Having thus described my invention what I claim 1s:

1. A gas turbine unit, comprising a series of mechanically independentmeans for compressing the gas in stages, means for adding ener of heatto the gas after compression, a series of means for expanding thecompressed gas in stages down to an appropriate degree, each compressingmeans being mechanically coupled to one of the expanding means, anengine mechanically independent of said means for compressing andexpanding the' gas, and means for conducting the degree, eachcompressing gas after final expansibnas a drivingfluid to the saidindependent engine. A

2. A gas tur ine unitcomprising means for gradually compressing the gasin separate stages connectedin series but mechanically independent. ofone another, means for adding energy of heat to the gas atsuitableplaces after compression, means for expandlng the gas gradually to greein separate stages connected in series but mechanically independent ofone anan appropriate deother,means for mechanically coupling togetherthefirst compressing means in the Sc ries of compression stages with thelast'expanding means in the stages of expansion,

means for mechanically coupling together 2 the second compressing meanswith the last but one expanding means, and so on, a drivingenginemechanically independent of said compressing and expanding means,and means for conducting the so expanded gas as a driving fluid to thesaid engine.

3. A gas. turbine unit, comprising compressors for gradually compressingthe gas through a series of stages, said compressors being mechanicallyindependent of one another, means for adding energy of heat to the gasafter compression, turbines for expanding the so compressed gas througha series of stages down to an appropriate degree, said turbines beingmechanicallyindependent of one another, means for coupling mechanicallytogether the first compressor in the series of compression stages withthe last turbine in the "series of expansion stages, means for couplingmechanically together the second compressor with the last but oneturbine, and so on, a driving engine mechanically independent of saidcompressors and turbines, and means for conducting the so expanded gasas a driving fluid to said engine.

4:. A gas turbine unit, comprising a series of mechanically independentturbo compressors for compressing air in stages, means for ducting thegases after expansion in said ent engine.

5. A' gas turbi e unit, comprising a. series of mechanicallyghiidependent means for compressing air in stages, means for cooling thegas between said stages, means for adding energy of heat to the air bycombustion after the last compression, a series of means for ex-''anding the compressed air and gases of comustion in stages down to anappropriate means being me stages asa driving fluid to the saidindependmeans, an engine led to one of the expanding mechanicallyindependent of said compressing and expanding means,

chanically coup and means for conducting the gases afterexpansion insaid stages as a driving fluid to the said independent engine.

6. A gas turbine unit, comprising a series of mechanically independentmeans for com:

pressing air in stages, means for cooling the air between said stages, aseries of means for expanding the compressed air in stages down to anappropriate degree, each compressing means being mechanically coupled toone of the expanding means, means for adding en ergy of heat to the airby combustion between two of t e expanding stages, an engine mechanica1y independent of said comressmg and expanding means, and means orconducting the gases after expansion in said stages as a driving fluidto the said independent engine;

In testimony whereof I have signed my name to this specification.

i IBIS WILLIAM AEGIDIUS ELLING.

